<form class="form-horizontal" method="post">
    <fieldset>
        <legend>用户登录</legend>
        <div class="control-group">
            <label class="control-label" for="username">用户名</label>
            <div class="controls">
                <input type="text" class="input-xlarge" id="username" name="username">
            </div>
        </div>
        <div class="control-group">
            <label class="control-label" for="password">密码</label>
            <div class="controls">
                <input type="password" class="input-xlarge" id="password" name="password">
            </div>
        </div>
        <div class="form-actions">
            <button type="submit" class="btn btn-primary">登录</button>
        </div>
    </fieldset>
</form>